Antenna



made at T1 and T2, the loops 29 and 30 are connected to the transmission lines at point P and Q, the instantaneous current distribution being indicated by the arrows. A the point R is located at the point of electrical symmetry and the connections to transmission line 32 are at point R with transmission line 32 mounted substantially perpendicularly to the plane of loops 29 and 39 at the point R, the coupling to loops 29 and 39 is made in a symmetrical manner without disturbing the current distribution.

With the two loops 29 and 30 of Figs. 2, 3 and 4 or of the loops II and 12 of Fig. 1 being connected in phase opposition, the two lobed pattern indicated in Fig. 1 is produced. When the planes of the two loops are horizontal, there is maximum response to horizontally polarized waves and a high discrimination against Vertically polarized waves, and similarly when the plane of the loops is vertical the antenna possesses high discrimination against horizontally polarized waves with maximum response to vertically polarized waves. Thus, the antenna according to this invention may be utilized as a direction finder antenna or as a beacon in association with radio object-locating systems.

It has been found that overall loop dimensions E and D (Fig. 2) of 16 and 13 inches respectively are satisfactory for operation as a direction-finding antenna in the frequency range of 100 to 200 megacycles (per second) when the loops are resonated. A satisfactory outer diameter of the loop sections 25, 29, 2'! and 23 is about 1.5 inches.

While there has been described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that variou changes and modifications may be made therein without departing from the invention.

What is claimed is:

1. An antenna comprising two substantially E- shaped sections facing each other with the center branches thereof joined to efiectively form two balanced symmetrically connected loops lying in the same plane, one of said E-shaped sections comprising a single wire conductor, the other of said sections comprising a coaxial conductor having an inner conductor and an outer concentric conductor, the ends of the free end branches of said single wire conductor being slightly spaced from the adjacent ends of said outer conductor, the ends of said inner conductor extending beyond said outer conductor and connected to the adjacent ends of said single wire conductor to complete each of said loops, means for transmitting electromagnetic energy to and from said loops, said means being coupled at the point of electrical symmetry of said two loops whereby said current flowing in one of said loops is in phase opposition to that in the other loop, said antenna thereby having maximum response to energy polarized in the plane parallel to the common plane of said loops and possessing high discriminatoin against energy polarized in the plane perpendicular to that of said loops.

2. An antenna as claimed in claim 1 wherein said transmitting means comprises a coaxial transmission line mounted perpendicularly and connected to the center branch of said loops at the point of electrical symmetry of said loops, the inner and outer conductor of said coaxial transmission line being connected to the inner and outer conductors respectively of the center branch of said coaxial section.

3. An antenna for translating electromagnetic energy polarized in a single plane comprising two similar, co-planar conductors forming loops connected in parallel wtih each other, said conductors being disposed as mirror-images of each other, transmission line means coupled to the portions of each of said conductors which are spaced furthest from one another for feeding electromagnetic energy to each of said conductors, and means including said transmission line means for causing current to flow clockwise around one loop and counter-clockwise around the other loop.

4. An antenna for translating electromagnetic energy polarized in a single plane comprising two similar, co-planar conductors forming loops connected in parallel with each other, said loops being disposed a mirror-images of each other, each loop comprising a first portion consisting of a coaxial line and a second portion consisting of a single conductor, said single conductor being connected at one end to the inner conductor of said line at the end of said line adjacent said one end, and said single conductor being connected at its other end to the outer conductor of said line at the end of said line adjacent said other end of said single conductor, and means coupled between the inner and outer conductor of each line near the portion thereof where its outer conductor is connected to said single conductor for supplying electromagnetic energy to said antenna.

5. An antenna for translating electromagnetic energy polarized in a single plane comprising two similar, co-planar conductors forming loops connected in parallel with each other, said loops being disposed as mirror-images of each other and each loop consisting of symmetrical halves, one of said halves of each loop consisting of a coaxial line and the other of said halves consisting of a single conductor having substantially the same diameter as that of the outer conductor of said line, said single conductor being connected at one end to the inner conductor of said line at the end of said line nearest said one end, and said single conductor being connected at its other end to the outer conductor of said line at the end of said line nearest said other end of said single conductor, the portions of said loops where said center conductor is connected to said single conductor being substantially the furthest spaced portions of said antenna, and means coupled between the inner and outer conductors of each line near the portion thereof where its outer conductor join said single conductor for supplying electromagnetic energy to said antenna.

JOHN D. KRAUS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,082,812 Worrall June 3, 1937 2,289,856 Alford July 14, 1942 2,354,332 Polydorofi July 25, 1944 2,391,026 McGuigan Dec. 18, 1945 2,405,123 Fyler Aug. 6, 1946 FOREIGN PATENTS Number Country Date 149,532 Great Britain Aug. 19, 1920 519,350 Great Britain Mar. 21, 1940 OTHER REFERENCES R. C. A. Review, vol. VI, No. 4, April 1942, article by W. L. Carlson, page 445. 

